Latent buoyancy system

ABSTRACT

Submerged objects are recovered by a latent buoyancy system including LiH or another chemical reactive with water to evolve a gas and form an inert reaction product, an annular aluminum screen containing the chemical, and a closed, watertight, annular housing containing the screen and chemical. The chemical reaction is initiated by admitting water through one or more openings formed at a desired time on the inside of the annular housing. The gas inflates a cylindrical flotation bag and the reaction product is permitted to escape to provide maximum lift. The lower end of the bag hangs free and is not stressed by the payload; and it is well above the chemical, so that the gas collected by the bag first passes through water and is cleaned, scrubbed and cooled.

United States Patent 91 Baccaglini et al.

[ LATENT BUOYANCY SYSTEM [75] Inventors: Russell C. Baccaglini, Oakland;

Kenneth J. Rogers, Boonton, both of NJ.

[73] Assignee: Ocean Recovery Systems, Inc.,

, Morristown, NJ.

[22] Filed: Nov. 5, 1971 [21] Appl. No.: 195,981

[52] US. Cl. 114/54 [51] Int. Cl. B63c 7/02, B63c 7/26 [58] Field of Search 9/8 R, 9; 23/282; 123/657, 646; 114/50, '54

[56] References Cited UNITED STATES PATENTS 2,581,693 6/1971 Basset 9/9 3,463,113 8/1969 Feyling 9/9 x 3,130,703 4/1964 Thompson 9/8 R X 3,667,417 6/1972 Clinkenbeard... 9/9 X 3,554,707 1/1971 Holmes et al.... 23/282 2,531,657 11/1950 Tobler 23/282 3,657,752 4/1972 Davidson et al. 9/9

3,540,854 11/1970 Brooke et al. 423/657 X 2,721,789 10/1955 Gill 423/657 X 3,229,291 1/1966 Dellaria et al. 9/8 R 3,293,676 12/1966 Link 9/8 R Dec. 11, 1973 3,566,426 3/1971 Davidson et al. 9/9 3,659,299 5/1972 Davidson et al. 9/8 R 3,372,996 3/1968 Barrett et al 3,496,580 2/1970 Gulmon et al.. 3,346,506 10/1967 Beumel 3,613,616 10/1971 Basset 9/9 Primary ExaminerMilton Buchler Assistant ExaminerGregory W. OConnor Att0rneyGranville M. Brumbaugh et al.

[57] ABSTRACT Submerged objects are recovered by a latent buoyancy system including LiH or another chemical reactive with water to evolve a gas and form an inert reaction product, an annular aluminum screen containing the chemical, and a closed, watertight, annular housing containing the screen and chemical. The chemical reaction is initiated by admitting water through one or more openings formed at a desired time on the inside of the annular housing. The gas inflates a cylindrical flotation bag and the reaction product is permitted to escape to provide maximum lift. The lower end of the bag hangs free and is not stressed by the payload; and it is well above the chemical, so that'the gas collected by the bag first passes through water and is cleaned, scrubbed and cooled.

1 Claim, 8 Drawing Figures maria. II

PATENTEDUECH I975 SHEEI 10F 3 Ww m & 3

PATENIEIIIIEII I I915 3.771.692

SHEET 2 OF 3 RADAR REFLECTIVE BALLOON F/(g. 2

XENON FLASHE)R7 PREssuRE .54 sENsITIvE GAS DEVICE GENERATOR ELECTRICAL CONNECTION /z I'I lg gw GAS GAS GENERATOR flz GENERATOR J4 LANYARD BALLOON GAS GENERATOR F/G 5 PAYLOAD GAS GENERATOR/ ELECTRICAL CONNECTION PING PAYLOAD 54 7 ER WW WAW/KM TIMING GAS l F/G. 7 DEVICE j GENERATOR ELECTRICAL CONNECTION PAY LOAD v '1 LATENT BUOYANCY SYSTEM.

BACKGROUND or THE INVENTION This invention relates to the recovery of submerged objects and, more particularly, to a novel and highlyeffective method and apparatus facilitating the prompt, safe, reliable and economical recovery of submerged objects regardless of the depth of submergence.

The recovery of submerged objects, often under emergency conditions, is extremely important not only interms of the cost of material (boats, oceanographic instruments, practice torpedoes, etc.) but also and especially in terms of human lives. Many submariners, for example, have lost their lives when, upon failure of the primary buoyancy control systems, no adequate emergency buoyancy system was available.

A number of ways of recovering submerged objects are known, including displacement of water by pressurized gas vented into a flexible bag or rigid ballast tank or by structural foamed plastic; the use of fixed buoyancy (as by dropping solid ballast or by severing a restraining tether); and the use of propulsive devices capable of flying the submerged object up or down. These various conventional techniques are discussed in an article by Fulton et al. entitled Buoyancy and Recovery on Command and published in Proceedings of the Sixth Annual Conference of the Marine Technology Society, June 29, 1970, pages 73-80 of Vol. 1. As this paper and a subsequent paper of Fulton et al. entitled fA New Form of Gas Generating Buoyancy Device and published in Proceedings of IEEE International Conference of Engineering in the Ocean Environment, Sept. 1970, pages 102-104, indicate, the best technique is often to employ a latent buoyancy system including a water-reactive fuel. v

One such system is .disclosed in a U.S. Pat. to Davidson et al. No. 3,566,426, issued Mar. 2, 1971, In this system, a manifold fixed to a bottom cover and to a central open standpipe contains a number of fuel cartridges into which a water-reactive fuel is placed. A chemical reaction is initiated by opening the cartridges and exposing the fuel to water. The reaction product is retained in the manifold, and the evolved gas inflates a bag attached to the bottom cover and a top cover. Stress on the inflated bag is relieved to some extent by a supplemental bag sleeve and an axial lift cable connecting the top and bottom covers.

Latent-buoyancy recovery systems known heretofore have advanced the art of recovering submerged objects but suffer from a number of deficiencies. For example, since the reaction of the fuel with water is exothermic, the evolved gas is hot and apt to damage the flotation bag and to present certain dangers to the personnel who make the recovery. Also, inefficient geometrical arrangements of prior-art systems make them inconvenient to store and transport and fail to promote efficient reaction of the chemical with water. Moreover, the retention of dense, inert reaction products within the system decreases the lift that would otherwise be provided. In addition, the prior-art devices fail to achieve adequate separation of the load-bearing and buoyancy functions, with the result that deformable and relatively weak parts, such as the flotation bag, are subject ,to stress damage. Prior-art devices tend to be damaged in use to such an extent that their reuse is impracticable or at least not very economical.

SUMMARY OF THE INVENTION An object of the pres'ent'invention is to remedy the deficiencies of prior-art systems noted above. In particular, an object of the invention is to provide a safe, reliable and economical way of recovering submerged p'ayloads promptly, regardless of their depth of submergence.

The foregoing and other objects of the invention are attained by the provision of a gas generator comprising a chemical reactive with-water to evolve a gas and form an inert reaction product, a screen containing the chemical, and a closed, watertight housing containing the screen and chemical. Means is provided for forming at least one opening in the housing at a desired time when the housing is submerged to permit entry of water into the housing and the screen for reaction with the chemical. The screen has a mesh of such a size and is so mounted with respect to the opening as to'retain the chemical prior to its reaction with water and to permit the gas and the reaction product to escape from the screen and the container.

The screen is preferably made of a material promoting the efficiency of the reaction of the chemical with water. Thus, where the chemical is lithium hydride ('LiH), the screenis preferably made of aluminum.

The screen and the housing are annular, and the opening is formed on the inside portion of the annular housing, since this geometry is found to provide significant advantages.

Before the initiation of the chemical reaction, the watertight integrity of the'housing'is maintained by a hollow, perforated post passing through the housing in watertight relation thereto and a shearing bolt and adapter screwed together and respectively passing through opposite ends of the post in watertight relation thereto. Biasing means mounted between the post and the adapter exerts a force tending to eject the adapter'from the post, but the shearing bolt secures the adapter within the post. By means of an explosive responsive to an electrical signal or by any other suitable means, the shearing bolt can be sheared off at a desired time when the housing is submerged. The force of the explosion and the biasing means eject the adapter from the post. This permits water to flow through the hollow post for reaction with the chemical and also permits deployment of a flotation bag which collects the gas evolved during the chemical reaction and provides lift. After the flotation bag is deployed, a top cover to which the upper end of the bag is attached remains connected to the housing by a flexible connector such as a rope. The lower end of the bag is positioned in such a manner as to collect the evolved gas, yet it hangs free and is not stressed by the payload; and it is well above the gas generator, so that the gas collected by the bag first passes through water and is cleaned, scrubbed and cooled.

BRIEF DESCRIPTION OF THE DRAWING An understanding of other aspects of the invention can be gained from a consideration of the following detailed description of the best mode contemplated by the inventors for carrying out the invention, in conjunction with the appended figures of the drawing, wherein:

FIG. 1 is a sectional view in elevation of a preferred embodiment of flotation apparatus constructed in accordance with the invention, the apparatus being shown prior to its actuation;

FIG. 2 is a diagrammatic view in elevation of the apparatus of FIG. 1 after its actuation and of a payload and signal means connected thereto;

FIGS. 37 are diagrammatic views illustrating various ways of actuating the flotation apparatus of the invention; and

FIG. 8 is a diagrammatic view of three devices of the type shown in FIG. 1 supporting a single payload after actuation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The flgures,'particularly FIG. 1, show a buoyancy system 10 comprising a gas generator 12 for evolving a gas that is collected by a flotation bag 14 to provide lift. The flotation bag 14 is stored in a collapsed state (FIG. 1) and inflated (FIGS. 2 and 8) as it collects the evolved gas.

As FIG. 1 shows, the gas generator 12 comprises a chemical l5 reactive with water to evolve a gas and form an inert reaction product, screen means such as an annular aluminum screen 16 containing the chemical 15, and a closed watertight annular cannister or housing 18 containing the screen 16 and chemical 15. As indicated in the patent to Davidson et al. referred to above, the chemical 15 can be any suitable waterreactive fuel including a hydride, oxide or peroxide of a metal such as lithium, sodium, calcium, potassium or aluminim and mixtures thereof; water-reactive fuels per se are conventional and available from commerical sources. The preferred fuel for use in accordance with the present invention is lithium hydride (LiH), which is extremely efficient but which has heretofore presented difficulties in use. It reacts exothermically with water according to the formula.

LiH (solid) H O (liquid) H2 (gas) LiOI-l (precipitate) Actuating means is provided for forming at least one opening in the housing 18 at a desired time when the housing 18 is submerged to permit entry of water into the housing 18 and screen 16 for reaction with the chemical 15 to liberate gas. The opening includes passages 22 in a center post 24 described in detail below. The screen 16 has a mesh of such a size and is so mounted with respect to the passages 22 as to retain the chemical 15 prior to its reaction with water and to permit the gas and the reaction product to escape via the passages 22 from the screen 16 and the housing 18. The passages 22 thus serve the dual function of admitting water for reaction with the chemical 15 and permitting escape of the gas and reaction product. The reaction of the chemical 15 with water is typically a violent one accompanied by much churning of the contents of the screen 16, so that the passages 22 readily serve this dual function.

Prior toactuation of the gas generator 12, the housing 18 is completely sealed so that it can be submerged to any depth without danger that water will leak into the housing for premature reaction with the fuel 15. The housing has a cylindrical outer wall 25, a generally flat but corrugated or otherwise contoured bottom wall a integral with the cylindrical outer wall, a top flange 25b flaring outwardly from the outer wall 25 at its upper end, and a removable cover 25c. The corrugations of the bottom wall 25a permit slight flexure when the device is submerged. The bottom wall 25a and cover 25c are formed with central openings 25d and 25e, respectively, to accommodate the center post 24, and the center post 24 is formed with a bore 24a to accommodate a shearing or explosive bolt 26 and adapter 27 and, as indicated above, with passages 22 so that water entering the bore 24a upon release of the adapter 27 in a manner described below can flow to the chemical 15. The shearing bolt 26 and adapter 27 are screwed together by threads 27" to form a unit of variable length adapted to be tightened firmly onto the center post 24 at opposite ends thereof. Shearing bolts are conventional and available from commercial sources. They contain an explosive, generally in the shank near the threads 27", which when set off severs the shank. The severing of the shearing bolt 26 actuates the device in a way described below.

The sealing of the bottom of the housing 18 is effected by any suitable means such as an O-ring 28 between the bottom wall 25a and the lower end of the center post 24 and a crush washer 32 between the head 26a of the shearing bolt 26 and an interior shoulder 24b near the lower end of the center post 24. A number of hexagonal socket-head machine screws 33 and a backing ring 33 compress the O-ring 28', and the head 26a of the shearing bolt 26 compresses the crush washer 32 when the shearing bolt 26 is screwed into the adapter 27 by means of the threads 27".

The sealing of the top of the housing l8 is effected by any suitable means such as an O-ring 28 between the housing cover 250 and the housing flange 25b, an O- ring 29 between the housing cover and the post 24, and an O-ring 30 between a conical surface 27a of the adapter 27 and an interior shoulder 24c of the center post 24. A number of hexagonal-head bolts 31 compress the O-ring 28, a number of hexagonal-head machine screws 33" compress the O-ring 29, and the conical surface 27a of the adapter 27 compresses the O-ring 30 when the adapter 27 and shearing bolt 26 are screwed together by means of the threads 27".

The housing 18 is loaded not only with the fuel 15 as indicated above but also with a pure oil (i.e., an oil that is dry and contains no oxidizing contstituents such as acids) so that there are no voids in the housing 18. Preferably, a mineral oil 15' is used. Since oil is substantially incompressible, the sealed housing 18 can be submerged to any depth without danger of damage. Moreover, since oil is less dense than water, it reduces the underwater weight of the apparatus 10 and facilitates the attainment of the desired buoyancy prior to actuation of the system, which is generally neutral or very nearly neutral. Although the other parts of the apparatus, except for a float 92 described below, are denser than water, the mineral oil, if enough is employed (i.e., if the space within the container to be filled by oil is large enough in proportion to the weight of the device), gives the apparatus as a whole neutral or even positive buoyancy. The oil, being pure as indicated above, also protects the chemical 15 during storage.

An upper load-bearing member 34 in the form of a mounting eye 36 having an adapter block 38 attached thereto is connected to a stud 39, which in turn is screwed into the adapter 27. A top cover 40 is connected to the load-bearing member 34, and the upper end of the collapsible flotation bag 14 is connected to the top cover 40 in gas-tight relation. Prior to actuation, the bag 14 is stored therein in a collapsed state, as shown in FIG. 1.

Biasing means such as an expansion coil spring 44 is mounted between the post 24 and the adapter 27 and exerts a force tending to eject the adapter 27 from the post 24. More particularly, the lower end of the spring 44 abuts a shoulder 46, and the upper end abuts the lower of a pair of spacers 48 which in turn abut a shoulder 50 formed on the adapter 27.

The shearing bolt 26 securing the adapter 27 within the post 24 constitutes a part of the actuating mechanism 20. An electrical lead 54 also constituting a part of the actuating mechanism 20 is provided for supplying an electrical pulse at a desired time thereby causing the shearing bolt 26 to separate when the housing 18 is submerged. The force of the explosion and the biasing means 44 eject the adapter 27 from the post 24, whereby the load-bearing member 34 and top cover 40 are freed, the bag 14 is deployed, and water is permitted to flow into the hollow central portion 24a of the post 24, through the several passages 22 and to the chemical for reaction therewith. A shorting plug 55 caps the electrical lead 54 during storage to prevent accidental discharge of the explosive within the shearing bolt 26 because of a build-up of static electricity.

A flexible connector such as a rope 56 connects the load-bearing member 34 to the housing 18 when the flotation bag 14 is deployed. The rope 56 passes through rope eyes 60 in the adapter block 38 and rope eyes 61 formed in lugs 62 attached to the cover 25c for the housing 18.

Thus, prior to the time when the flotation bag 14 is deployed, when the buoyancy system 10 is supported by the load-bearing member 34, the housing 18 is suspended from the load-bearing member 34, the stud 39, adapter 27, shearing bolt 26 and the post 24; and, after the flotation bag 14 is deployed, when the buoyancy system 10 is supported by the load-bearing member 34, the housing 18 is suspended from the load-bearing member 34 and the rope 56. In neither case is the bag 14 stressed. The rope 56 is sufficiently long in relation to the flotation bag 14 that the bag 14 when deployed is positioned above the gas generator 12 for inflation by the evolved gas and in spaced-apart relation to the gas generator 12, so that the evolved gas passes through water en route from the gas generator 12 to the flotation bag l4 and is thus cleaned, scrubbed and cooled. After the bag 14 is fully inflated, excess gas generated by the gas generator 12 is vented. Of course, if because of tipping, etc., some gas is lost from the bag 14, additional gas generated by the gas generator 12 reinflates the bag 14. Thus, some excess gas-generating capacity is desirable to assure that the bag 14 remains fully inflated. The excess generating capacity need not be great, because gas in the bag expands during the ascent through regions of progressively lower water pressure.

The lower end of the bag 14 hangs free in that it is not stressed to a substantial degree; it is, however, held in position over the gas generator 12 by a number of webs 70 (FIGS. 1 and 2) each in the shape ofa strip of material folded to form a V. To secure each web 70 to the bag 14 and housing 18, a pair of grommets 72 are attached to the lower end of the bag 14, and a grommet 74 is passed through each web 70 at a point near the vertex of the V and held by nuts 76 on the bolts 31.

Washers 82 above the housing cover 250 and below a backing ring 84 facilitate tightening by means of the nuts 76 and bolts 31. A number of locking arrangements such as the one shown, such as 9 bolts similar to the illustrated bolt31, are placed around the periphery of the upper portion of the housing 18 to secure the housing cover 25c, and some or all of them may be used to secure a web so that the bag 14 is properly positioned without being stressed to a substantial degree.

The float 92 can be made of any water-resistant, light-weight material such as a depth-resistant syntactic foam and is mounted by one or more mounting pads 94 comprising a sponge rubber cemented by a silicone rubber sealer to the top cover 40. The float 92 further facilitates achieving neutral buoyancy.

Various meanselectrical, hydraulic, mechanical, acoustic, etc-can be employed for forming the necessary opening or openings admitting water to the chemical 15. For example, in order to close an electrical circuit through the electrical lead 54, thereby exploding the shearing bolt 26, a pressure-sensitive device 95 (FIG. 3), can be employed, whereby the opening -is formed and the gas generator 12 is actuated when a hydrostatic pressure equal to or greater than a predetermined hydrostatic pressure acts on the buoyancy system. Conventional pressure-sensitive devices are available commercially which generate an electrical signal when subjected to a hydrostatic pressure equal to or greater than a predetermined hydrostatic pressure. This signal, supplied to the line 54, actuates the gas generator 12.

Alternatively, a vertical-velocity-sensitive device 96 (FIG. 4) can be employed, whereby the opening is formed when the buoyancy system descends at a rate equal to or greater than a predetermined rate. Conventional vertical-velocity-sensitive devices are available commercially which generate an electrical signal when they descend at a speed equal to or greater than a predetermined vertical velocity. This signal can be supplied to the line 54 to actuate the gas generator 12.

Or, a lanyard 97 (FIG. 5) may be provided so that the opening is formed mechanically (without the use of an explosive) when the lanyard is pulled by an operator, a diver, for example, stationed at a distance from the buoyancy system.

Again there may be provided means 98 (FIG. 6) mounted on a surface vessel 99 for generating an acoustic signal. The acoustic signal receiver can be in the form of a conventional pinger 100 attached to the payload and supplying an electrical signal to the gas generator 12 through the electrical lead 54 in response to receipt of the acoustic signal. The acoustic signal can be coded and the pinger 100 designed to respond only to a properly coded signal so that random ocean noises will not actuate the gas generator 12. The generator and pinger are conventional and available from commercial sources.

Another possibility is to employ a conventional timing device 101 (FIG. 7) for generating a timing signal upon the passing of a predetermined period of time. The timing signal is supplied to the electrical lead 54 to actuate the gas generator 12. Such timing devices are of course conventional and available from commercial sources.

When the apparatus according to the invention is lifted out of the water by means of the upper loadbearing member 34, the gas generator 12 is suspended from the attachment means, 'the attachment means comprising the adapter block 38, stud 39, adapter 27, shearing bolt 26 and center post 24 prior to the time the gas generator 12 is actuated and comprising the rope 56 after the gas generator 12 is actuated and the flotation bag 14 is deployed. Thus, whether or not the gas generator 12 has been actuated, when the device is suspended from the upper load-bearing member 34 (as by passing a rope through the upper padeye 36), a payload can be suspended from the lower load-bearing 34 (as by passing a rope through the lower padeye 36) without imposing a stress on the flotation bag 14. The lower padeye 36' is screwed into the center post 24 by threads 36".

When the payload arrives at a point near the surface of the water, a signal is preferably given in accordance with the method of the invention (FIG. 2). This signal can be given by, for example, inflating a radarreflective ballon 110 with a lighter-than-air gas evolved by a ballon gas generator 1 12 and permitting the ballon to rise above the surface of the water. In addition or in the alternative, a xenon light 1 14 can be flashed continuously or intermittently above the surface of the water as a signal upon arrival of the payload at a point near the surface of the water. Other signal devices that can be used, singly or in any desired combination, are dye cakes, pyrotechnic flares, radio signals, and underwater signals. Underwater signals canbe intended for reception by equipment on a surface vessel or by equipment on a submersible vessel such as a submarine.

It is of course within the scope of the invention to attach the gas generator 12 to the payload before submergence of the payload (as in the case, for example, of a practice torpedo, where it is anticipated that the payload may be lost) or after submergence of the payload (as in the case, for example, of rescue ofa disabled underwater device which was not previously equipped with the apparatus of the invention). It is also within the scope of the invention to provide for actuation of the device by personnel within a disabled vessel, so that they are not dependent on outside support for rescue.

It is further contemplated that there may be attached to the payload a plurality of gas generators 12 each comprising a closed, watertight housing 18 in accordance with the disclosure herein and each containing the chemical 15, so that the lift is multiplied. In the example of FIG. 8, three gas generators 12 each with its own flotation bag 14 are provided.

Preferably, the housing 18 as well as the payload is recovered, and the housing is serviced and reused. Servicing of the housing 18 involves cleaning, drying, reloading with chemical and oil, heating to cause trace impurities to react, and sealing.

Thus in accordance with the invention a novel and highly-effective method and apparatus facilitating recovery of submerged payloads are provided. Improved gas generation is provided, since the water flowing through the passages 22 surrounds the fuel 15 by flowing into the spaces between the screen 16 and bottom, top, and outer walls of the housing. Many modifications of the representative embodiments of the invention disclosed herein will readily occur to those skilled in the art upon a reading of the present disclosure. Accordingly, the invention is to be construed as including all of the embodiments thereof within the scope of the appended claims. We claim: 1. A buoyancy system comprising: a chemical reactive withwater; a closed, watertight housing containing said chemical; a hollow, perforated post passing through said housing in watertight relation thereto; an adapter passing through said post in watertight relation thereto; a load-bearing member connected to said adapter; atop cover connected to said load-bearing member; a collapsible flotation bag connected to said top cover and stored therein in a collapsed state; biasing means mounted between said post and said adapter and exerting a force tending to eject said adapter from said post; a shearing bolt securing said adapter within said post; actuating means by which said shearing bolt can be sheared off at a desired time when said housing is submerged, allowing said biasing means to assist in ejecting said adapter from said post, whereby said load-bearing member is freed, said flotation bag is deployed, and water is permitted to flow through said post to said chemical for reaction therewith; and rope means connecting said load-bearing member to said housing when said flotation bag is deployed, whereby, prior to the time when said flotation bag is deployed, when said buoyancy system is supported by said load-bearing member, said housing is suspended from said load-bearing member, said adapter and said post, and, after said flotation bag is deployed, when said buoyancy system is supported by said load-bearing member, said housing is suspended from said load-bearing member and said rope means. 

